Means for feeding fibrous materials



A ril 29, 1969 EENWOOD ET AL 3,440,690

MEANS FOR FEEDING FIBROUS MATERIALS Filed Nov. 5, 1966 Sheet of 2 April 29, 1969 R. GREENWOOD E L 3,

MEANS FOR FEEDING FIBROUS MATERIALS Filed NOV. 5, 1966 Sheet United States Patent O" MEANS FOR FEEDING FIBROUS MATERIALS Robert Greenwood, Whalley, near Blackburn, and Walter Howarth, Haslingden, Rossendale, England, assignors to T.M.M. (Research) Limited, Oldham, England, a

British company Filed Nov. 3, 1966, Ser. No. 591,900 Int. Cl. D01h 5/32 U.S. Cl. 19-240 5 Claims ABSTRACT OF THE DISCLOSURE Apparatus for controlling the mass per unit length of fibrous material fed to a textile drafting machine. The apparatus utilizes a draft control means which is responsive to a deviation of the measured mass per unit length from a predetermined mass per unit length to vary the draft of the control drafting system to thereby reduce said deviation.

This invention relates to improved means for controlling the mass per unit length of fibrous material fed to a textile drafting operation.

Attempts have been made previously to control the mass per unit length of fibrous material being subjected to a drafting operation. In one arrangement hitherto proposed the mass per unit length of a fibrous material being fed to a drafting system is measured and the draft in the drafting system adjusted in response to any deviations in the measured quantity to correct the deviations. This arrangement is an open loop control system and suffers from the defects common to all open loop systems, that is to say, there is a tendency to drift away from the predetermined desirable mass per unit length and there is usually inaccurate amplitude correction at some response frequencies. It has also been proposed to measure the output from a drafting system and to alter the draft in the drafting zone in response to deviations in the measured output so as to correct such deviations. This is a closed loop system but whilst it overcomes some of the disadvantages of the open loop system it has been found that attempts to alter the draft in the main drafting system when processing at high speeds have led to complications and unsatisfactory correction.

An object of the present invention is to provide improved means for correcting deviations in the mass per unit length of fibrous material before it is fed to a drafting operation and without making any alterations to the draft in the main drafting system.

According to the invention there is provided a textile drafting system comprising a main drafting system, measuring means for measuring at a measuring position the mass per unit length of fibrous material being fed to the main drafting system, a control drafting system acting on said fibrous material before it reaches the measuring position, and draft control means responsive to deviations of the measured mass per unit length from a predetermined mass per unit length to vary the draft in said control drafting system to reduce or tend to reduce said deviations.

In a preferred embodiment of the invention, a plurality of slivers are processed in side-by-side formation through the control drafting system and then through the main drafting system, the slivers being combined as they pass through the measuring position so that the combined mass per unit length is measured.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which:

FIG. 1 is a plan view, part of which is in diagrammatic 3,440,690 Patented Apr. 29, 1969 form, of a textile drafting system according to the invention and FIG. 2 is a perspective view of part of the apparatus shown in FIG. 1.

Referring to the drawings, a drawframe 11 is fed with slivers 12 from eight sliver cans 13 arranged behind the drawframe, four of the cans being positioned along one side of a sliver supporting table 14 and the other four cans being positioned along the other side of the table. The table 14 is arranged with one end behind the drawframe 11 and the slivers 12 from the cans are fed on to the table by driven creel rollers (not shown) and guided by guide rollers 15. On leaving the sliver supporting table 14, the slivers are fed through a control drafting system 16 having a pair of back rollers 17 and a pair of front rollers 18, the relative speeds of the front and back rollers 17 and 18 being such as to provide a draft of, say, between 1 and 2. The slivers 12 emerging from the control drafting system 16 are passed over a guide tray 19 having side walls converging to form a trumpet 20, the slivers 12 converging into the trumpet and issuing from it at approximately single sliver width. From the trumpet 20 the combined slivers are fed to the nip of a pair of measuring rollers consisting of a top tongued roller 21 and a bottom grooved roller 22, the former of which is so mounted as to be vertically displaceable in dependence upon the thickness or mass per unit length of the combined slivers 12 passing therethrough. The combined slivers 12 on leaving the tongued and grooved rollers 21 and 22 are separated by passing them under and over two bow shaped spreader guides 23 and 24 and then fed via assisting rollers 25 and 26 to the main drafting system to the drawframe.

The top tongued roller 21 is coupled to a transducer 27 which is arranged to generate an electrical signal which is a measure of the displacement of the top roller 21 from a desired thickness setting and is related in phase angle to the direction of displacement from the desired thickness setting. The electrical signal generated by the transducer 27 is fed to an amplifier 28 where the signal is amplified and the amplified signal is applied to drive servo motor 29 the output shaft of which is arranged to drive through re duction gearing 30 an input shaft 31 to a variable speed unit 32 which also has a constant speed input 33 driven via shaft 34 of the assisting roller 25 and gears 35 from the main drafting system of the drawframe, which also provides through chain and sprocket drives 36 and 37 a constant speed drive to the bottom grooved roller 22 and to the front rollers 18 of the control drafting system 16. The variable speed output of the variable speed unit is arranged to drive through a chain and sprocket drive 38 the back rollers of the control drafting system as well as the creel rollers (not shown).

In operation, the eight slivers 12 from the sliver cans 13 are fed to the drawframe 11 via the control drafting system 16 and the tongued and grooved rollers 21 and 22. Upon a reduction in the thickness or mass per unit length of the combined slivers 12 passing through the tongued and grooved rollers 21 and 22 the top tongued roller 21 is lowered resulting in a signal at the transducer 27 of zero phase angle. As a result, servo motor 29 will drive in say an anticlockwise direction, causing an increase in speed on the variable speed output of the variable speed unit 32, and the arrangement is such as to cause an increase in the speed of the back rollers 17 of the control drafting system 16 and a reduction in the draft of the latter which will restore or tend to restore the thickness of the combined slivers to the desired thickness setting. In response to an increase in the thickness of the combined slivers 12 above the desired thickness setting the phase angle of the signal from the transducer changes through causing clockwise rotation of the servo motor 29 a reduction in 3 the speed of the back rollers 17 of the control drafting system and an increase in draft which will bring or tend to bring the combined slivers 12 back to the desired thickness.

The embodiment of the invention hereinbefore described may be used behind any standard textile drafting system and will control long-term and medium-term regularity of the fibrous material fed to (and therefore delivered from) the main drafting system.

In addition to correcting normal variations in sliver thickness the embodiment of the invention hereinbefore described will correct for a missing sliver or an extra sliver fed in during a piecing operation.

Although in the embodiment hereinbefore described a servo motor and reduction gearing have been employed it will be appreciated that the draft of the control drafting system can be varied by the use of clutches in a manner similar to that described in our British Patent No. 941,405.

What we claim as our invention and desire to secure by Letters Patent is:

1. A textile drafting system for drafting textile slivers, comprising sliver supply means for supplying a plurality of slivers, a control drafting system to which the slivers from the sliver supply means are fed initially in side-byside relationship therethrough, measuring means for measuring the combined mass per unit length of the slivers delivered by the control drafting system, a main drafting system to which said slivers are passed after passage through said control system and measuring means, and draft control means responsive to a deviation of the measured mass per unit length from a predetermined mass per unit length to vary the draft of the control drafting system to reduce said deviation, said control drafting system including a pair of front rollers and a pair of back rollers, a constant speed drive, means drivably connecting said front rollers to said constant-speed drive of said main drafting system, a variable-speed unit, means drivably connecting said back rollers to said variablespeed output shaft of said variable-speed unit, and means drivably connecting a constant speed input shaft of said variable-speed unit to said constant-speed drive of said main drafting system, said draft control means further including a transducer arranged to generate an electrical signal which is a measure of the deviation of the said measured mass per unit length from said predetermined mass per unit length, and a servo motor responsive to said signal and drivingly connected to a variable-speed input shaft of said variable-speed unit to vary the speed of the variable-speed output shaft of the unit and thereby the speed of the back rollers of said control drafting system.

2. A textile drafting system according to claim 1, wherein said measuring means comprises a pair of measuring rollers one of which is formed with a peripheral groove and the other of which is formed with a peripheral tongue, wherein the combined slivers are arranged to be fed to the nip between the two rollers, and wherein one of the rollers is mounted so as to be biased against the other roller and displaceable away from the other roller in dependence upon the thickness or mass per unit length of the combined slivers passing through said nip.

3. A system according to claim 2, wherein said measuring rollers are arranged one above the other and wherein the bottom roller is rotatable about a fixed axis and wherein the top roller is rotatable about a vertically displaceable axis in dependence upon the thickness or mass per unit length of the combined slivers passing through said nip.

4. A system according to claim 2, wherein said transducer is arranged to generate an electrical signal which is a measure of the displacement of the displaceable roller from a desired thickness setting and is related in phase angle to the direction of the displacement from the desired thickness setting.

5. A system according to claim 1, wherein the constant speed input to the variable speed unit is driven from the main drafting system, the latter driving the front rollers of the control drafting system.

References Cited UNITED STATES PATENTS 802,492 10/1905 Birch 19240 2,244,203 6/1941 Kern l9-65 2,608,725 9/1952 Strew 19-157 2,964,803 12/1960 Robinson 19-240 2,981,986 5/1961 Neil 19-240 3,038,216 6/1962 Naegeli 19157 XR FOREIGN PATENTS 68,315 11/1957 France. 930,873 7/1963 Great Britain.

DORSEY NEWTON, Primary Examiner. 

